The transportation of goods by truck, rig and trailers is a key industry in modern society. However, it is not unusual for the axle or axles on a trailer to become misaligned. This may occur on account of the trailer wheels striking an abutment, from the trailer body becoming bent, or from some other reason. Such out of alignment conditions of the axle or axles of a trailer may lead to rapid tire wear which may result in increased expenses for the trailer owner or create hazardous conditions which may cause jackknifing and make it difficult to control the trailer on the road.
Furthermore, there is a lateral drag on the back end of the trailer which in turn causes tire wear on the trailer tractors and difficulties in handling the tractor. Accordingly it is not unusual for tractors to run at excessive torquing. All of these conditions create unnecessary fuel consumption, deterioration in the life of the tractor, tires wearing prematurely, strain on engine parts and increased engine down time.
Accordingly, there is a need for devices to measure the distance between a plurality of axles on a trailer, and between the axles and the kingpin or coupling device such as a drawbar swivel eye. There is also a need for an improved method for aligning the axles on a vehicle.
There have been a number of arrangements heretofore which have been designed for aligning axles for trailers. For example some operators use a tape measure to measure the distance between the center line of the king pin and the ends of each axle. This tends to be inaccurate as the tape tends to sag. Furthermore obstacles under the trailer are encountered by the sagging tape making it difficult to obtain an accurate reading.
Other arrangements are shown in U.S. Pat. No. 2,479,723 which relates to a method and means for aligning the rear axles of trailers. Furthermore, U.S. Pat. No. 2,590,722 relates to a device for aligning the wheels and axles of a vehicle in relation to the line of draft of the vehicle.
Moreover, U.S. Pat. No. 2,632,256 relates to an axle alignment device while U.S. Pat. No. 2,845,718 relates to gauging and aligning devices for vehicle axles.
Another arrangement for aligning of axles of trailers is shown in U.S. Pat. Nos. 2,877,560, 3,088,214 and U.S. Pat. No. 3,137,076.
U.S. Pat. No. 3,162,950 also relates to a method and means for a trailer axle alignment while U.S. Pat. No. 3,279,084 relates to a trailer axle misalignment and wheel runout indicator and method.
Other arrangements for axle aligning are discussed in U.S. Pat. Nos. 3,325,905, 3,566,476, 3,686,770, 3,962,796, and U.S. Pat. No. 4,055,899.
U.S. Pat. No. 4,347,668 relates to apparatus for aligning the axles of trailers having an instrument case connected by an elongated spring-loaded cable to the trailer king pin and connected by a pair of cables to clips releasably fastened on space location to the trailer axle.
Furthermore, U.S. Pat. No. 4,413,420 relates to a vehicle geometry checking apparatus or U.S. Pat. No. 4,569,140 relates to a thrust line wheel alignment apparatus and method.
Moreover U.S. Pat. No. 4,800,651 relates to an apparatus and method for aligning axles with respect to the frame of the vehicle and for determining wheel camber thereof.
Furthermore, U.S. Pat. No. 4,942,667 illustrates a portable apparatus for aligning the axles of a tractor, a trailer, or other vehicle for detecting bins, bows, twists and other irregularities in vehicle frames which a light source has used to provide a reference plane from which measurements can be taken. Such arrangement illustrates a complicated and expensive means for aligning axles on a trailer.
Further, U.S. Pat. No. 5,125,164 relates to a portable axle and frame alignment tool while U.S. Pat. No. 5,157,838 shows a vehicle axle alignment instrument and method.
A tandem axle alignment device is illustrated in U.S. Pat. No. 5,367,778 while U.S. Pat. No. 6,021,576 relates to a trailer trammel. Finally, U.S. Pat. No. 6,233,837 relates to an axle alignment system which includes a transmitter, reflector and an indicator area.
These and other devices and methods described are relatively complicated and expensive means for aligning the axles on a trailer.